I. Field of the Invention
This invention relates generally to a vertical intersecting lightweight steel frame and, more specifically, to a vertical intersecting lightweight steel frame composed of several main frames and side frames, both frames have a elongated groove on the bottom. The mid portion of the main frame has a plurality of joint slots. A first oblique fold is formed vertically under the joint slot. An inserting tongue is on both ends of the side frame. A protrusion is stretched out from the flap of the side frame. The angle of the first oblique fold on both sides of the indention of the main frame is less than 45 degrees. A second oblique fold above the first oblique fold has an angle of 45 degrees. The angle of the protrusion of the side frame is also 45 degrees. Such structure makes the protrusion of the side frame match and attach firmly into the second oblique fold of the main frame. The whole structure is stronger and easier to assemble. The darkened area of the vertical connection between the main frame and side frame is kept undisclosed.
II. Description of the Prior Art
Heretofore, it is known that most of the ceilings of residential houses or offices are made of metal cranes to form lightweight steel frames, and the empty spaces are filled with plastic, wood or metal plates.
The known prior art, as shown in FIG. 5, is formed with a main frame a and side frame b. Main frame a and side frame b are made of metal cranes and pressed into an I shape. On the bottom the main and side frames have flap a1, b1 respectively that are stretched out and form elongated groove a2, b2. In the mid portion of the main frame are a plurality of joint slots a3. Vertically beneath the joint slot a3 is an indentation a4 extending from the elongated groove a2. An oblique fold a5 is at the front of the indentation a4 of the main frame a. On both ends of the side frame b are inserting tongue b3. On both ends of flap b1 of side frame b are protrusion b4. The inserting tongue b3 of the side frame b inserts into joint slot a3 of the main frame. The protrusion b4 at the end of the flap b1 under the side frame b vertically fastens to the elongated groove a5 of the main frame a. Such an arrangement can make the elongated groove b2 of the side frame b connect vertically to the elongated groove a2 of the main frame a. The connection is repeted until the frame structure covers the whole ceiling.
The elongated groove a2 of the main frame a and the elongated groove b2 of the side frame b, and the oblique fold a5 of main frame are painted in a dark color to emphasize the connection lines. The oblique fold a5 on both ends of the elongated groove a4 of the main frame a is bent from flap a1. The arrangement will weaken the indentation a4 of the main frame a. The whole structure might tend to twist and be unstable.
The indention a4 of the main frame a is pressed out from the main frame a. Therefore the structure around the indention a4 might tend not to be so strong and twist easily. After the protrusion b4 of the side frame b attaches to the oblique fold a5 on the indention a4 of the main frame a, the protrusion a4 of the side frame might be out of the alignment. The sharp edge of the protrusion a4 might cause injury during assembly.
The elongated groove b4 beneath the inserting tongue b3 of the side frame b connects to the oblique fold a5 of the main frame a. The indentation a4 of the main frame a is twisted easily after assembly. Since the oblique fold a5 of the main frame a is painted dark, the twist might cause the protrusion b4 of the side frame b to incompletely cover the oblique fold a5 of the main frame. The oblique fold a5 of the main frame a will expose the darkened area.
It is therefore a primary object of the invention to provide a vertical intersecting lightweight steel frame that has a second oblique fold above the first oblique fold. Such a scheme can provide a stronger structure after the side frames are mounted on the main frame.
It is another object of this invention to provide a vertical intersecting lightweight steel frame that has a second oblique fold above the first oblique fold of the main frame. Such an arrangement can cover the cross section of the main frame and the side frame properly to avoid the darkened area from exposure.